IDENTIFICATION OF NOVEL MDM2 BINDING PEPTIDES BY PHAGE DISPLAY

The oncogene mdm2 and its human homologue hdm2 bind to the tumour supp ressor protein p53 and inactivate its function as a transcription fact or. This has been implied as a possible mechanism for cancer developme nt in several tumours including human sarcomas. The mdm2-p53 interacti on is therefore a much persued target for the development of anti-canc er drugs. In order to find novel high affinity ligands for hdm2 which would interfere with its binding to p53 we screened phage display pept ide libraries for mdm2 binding phage. We found a series of 12 and 15me r peptides which interact strongly with hdm2. The peptide sequences sh ow striking homology with the previously established mdm2 binding site on p53, confirming that the peptide defined (18)TFSDLW(23) region is crucial for the interaction but that contact between the two molecules extends to position L(26) On p53. Free synthetic peptides derived fro m the phage selected sequences proved to be up to 100 times stronger i nhibitors of the p53-mdm2 interaction than the p53 derived wt-peptide in several ELISA-assays. This illustrates the potency of phage display libraries in the search for new peptide based lead structures designe d to mimic or inhibit therapeutically important protein-protein intera ctions.